Search NASA⌕ Search

SEARCH · Search NASA

Results for “EXTRATERRESTRIAL LIFE”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Extraterrestrial Organic Chemistry: From the Interstellar Medium to the Origins of Life

Extraterrestrially delivered organics in the origin of cellular life. Various processes leading to the emergence of cellular life from organics delivered from space to earth or other planetary bodies in the solar system will be reviewed. The focus will be on: (1) self-assembly of amphiphilic material to vesicles and other structures, such as micelles and multilayers, and its role in creating environments suitable for chemical catalysis, (2) a possible role of extraterrestrial delivery of organics in the formation of the simplest bioenergetics (3) mechanisms leading from amino acids or their precursors to simple peptides and, subsequently, to the evolution of metabolism. These issues will be discussed from two opposite points of view: (1) Which molecules could have been particularly useful in the protobiological evolution; this may provide focus for searching for these molecules in interstellar media. (2) Assuming that a considerable part of the inventory of organic matter on the early earth was delivered extraterrestrially, what does relative abundance of different organics in space tell us about the scenario leading to the origin of life.

Pohorille, Andrew↗
NASA NTRS2000

Detection of Extraterrestrial Ecology (Exoecology)

Researchers in the Astrobiology Technology Branch at Ames Research Center have begun investigating alternate concepts for the detection of extraterrestrial life. We suggest searching for extraterrestrial ecology, exoecology, as well as for extraterrestrial biology, exobiology. Ecology describes the interactions of living things with their environment. All ecosystems are highly constrained by their environment and are constrained by well-known system design principles. Ecology could exist wherever there is an energy source and living I things have discovered some means to capture, store, and use the available energy. Terrestrial ecosystems use as energy sources, light, organic molecules, and in thermal vents and elsewhere, simple inorganic molecules. Ecosystem behavior is controlled by matter and energy conservation laws and can be described by linear and nonlinear dynamic systems theory. Typically in an ecosystem different molecules are not in chemical equilibrium and scarce material is conserved, stored, or recycled. Temporal cycles and spatial variations are often observed. These and other -eneral principles of exoecology can help guide the search for extraterrestrial life. The chemical structure observed in terrestrial biology may be highly contingent on evolutionary accidents. Oxygen was not always abundant on Earth. Primitive sulfur bacteria use hydrogen sulfide and sulfur to perform photosynthesis instead of water and oxygen. Astrobiologists have assumed, for the sake of narrowing and focusing our life detection strategies, that extraterrestrial life will have detailed chemical similarities with terrestrial life. Such assumptions appear very reasonable and they allow us to design specific and highly sensitive life detection experiments. But the fewer assumptions we make, the less chance we have of being entirely wrong The best strategy for the detection of extraterrestrial life could be a mixed strategy. We should use detailed assumptions based on terrestrial biology to guide some but not all future searches for alien life. The systems principles of exoecology seem much more fundamental and inescapable than the terrestrial biology analogies of exobiology. We should search for exoecology as well as exobiology.

Jones, Harry↗
NASA NTRS2001

Exobiochemistry

Exobiochemistry is the putative biochemistry of extraterrestrial life. It suggests the possible energy and material bases of extraterrestrial life and could help detect it. The diverse biochemistry of Earth indicates that a wide range of exobiochemistry is possible on other planets. An exobiochemistry will probably use the same energy sources as Earths ecology, light, biological organic material, and more rarely abiotic chemicals. Extraterrestrial life will be based on familiar chemical principles and probably capture, store, and release energy using oxidation-reduction reactions. Extraterrestrial life will give chemical indications of its existence. Key elements will be concentrated, stored, and recycled, altering their availability and isotopic composition. Any significant departure from chemical equilibrium would be good evidence for exobiochemistry, but an integrated system of departures from the expected equilibrium would be better. Exobiochemistry can be expected to include closed biogeochemical cycles of the major life supporting elements and may well show the complex dynamic close-coupled interactions that characterize the terrestrial biosphere. Terrestrial biochemistry provides a basis for generalization and extrapolation but it does not set bounds on exobiochemistry. In exobiochemistry we can expect: 1. closed chemical cycles that recycle materials, nutrients, and catalysts, 2. organisms with complementary metabolisms that cooperate to close the chemical cycles, 3. a high probability of a carbon and water chemistry, but some possibility of a non-carbon or non-water chemistry in extreme environments, and, 4. life similar to bacteria more prevalent than higher plants and animals.

Jones, Harry↗
NASA NTRS2001

Using Artificial Life to Assess the Typicality of Terrestrial Life: Implications for Human Mission Planetary Protection

The extent to which extraterrestrial life questions can be addressed, in the absence of an actual example, rests in some measure on the extent to which terrestrial life is representative of life in general since we will likely have to draw heavily, if not completely, from terrestrial life research. One example of a practical question involving extraterrestrial life that arises in preparing for a human mission to another planet such as Mars, is trying to assess and minimize the possible adverse effects of the presence of humans on possible indigenous extraterrestrial life-forms. This paper will present some key planetary protection challenges for a human Mars mission and then focus on one possible approach for assessing the extent to which terrestrial life is representative of biological phenomena in general, informing perhaps, the level of confidence we might have in applying terrestrial research - to extraterrestrial life issues. The approach involves appealing to the relatively new field of Artificial Life (A-Life) to: (1) use what might be the most basic minimal set of life-defining characteristics in (2) a large number of open-ended Artificial Life simulations to generate a "life possibility space" (3) the products of which can be examined for their plausibility within the context of relevant constraining knowledge, so that (4) the remaining possibility space can be examined for its variability relative to terrestrial life, where low variability might suggest that terrestrial life is representative of life in general, and high variability would indicate otherwise.

Lupisella, Mark↗
NASA NTRS1962

LIFE IN EXTRATERRESTRIAL ENVIRONMENTS

The objective of this program was to establish whether terrestrial life forms can survive and thrive in extraterrestrial environments. Other than Earth, the only solar body capable of supporting terrestrial life appears to be the planet Mars. The conditions selected to simulate a Martian environment were determined by a literature search and were: 1) Light of > 4800-A wavelength 2) Temperature changes from a diurnal high of 30 °C to a nocturnal low to -60 °C 3) Atmosphere composed of 95% nitrogen, 4% argon, 0.3% carbon dioxide, and less than 1% oxygen and moisture. The organisms tested in thesimjulated Martian environment were: 1) Algae: Trebouxia erici 2) Bacteria: Clostridium tetani, Bacillus subtilis, and Escherichia coli 3) Bryophytes: the liverwort Marchantia polymorpha; the mosses Eurhynchium strigosum, Atrichum undulatum, Mnium sp., Brium sp., Grimmia sp., Pogonatum sp., and Polytrichum sp. 4) Lichens: Cladonia conoeraea, C. rangifernia, C. cristatella, C. pyxidate, Parmelia conspersa var. isidata, P. conspersa var. leucophora, Lecidea cyanea, Umbilicaria dillenii, Physcia hypoleuca, and Ramalina sp. T. erici survived for about 2 weeks. C. tetani and E. coli cells decreased rapidly in number, but the tetanus toxin remained active for the 127=day period of the experiment. B. subtilis cells increased in number. Of the Bryophytes, only one moss survived. Complete results for the lichens are not yet available. It is suggested that the observed color changes on the Martian surface may be explained in part by color changes in the surface vegetation as a function of moisture content.

Mars (Planet)↗
NASA NTRS1969

Life detection techniques.

Extraterrestrial life detection experiments integrated into single multipurpose space laboratory, including chemical analyses, metabolism identification, observation for molecular and/or cellular growth and replication

Young, R. S.↗
NASA NTRS1970

The coming search for life on Mars

Extraterrestrial life hypotheses, citing astronomical considerations, inorganic chemical evolution and prebiotic synthesis with emphasis on Mars exploration for microorganisms

Klein, H. P.↗
NASA NTRS1999

Asteroids and Aliens

Discussion of extraterrestrial life (ETL) and extraterrestrial intelligent life (ETI) is extraordinarily complex and mulitidisciplinary, in part because relevant questions involve both the origin/evolution of terrestrial life and the future of human civilization.

asteroids extraterrestrials↗
NASA NTRS1972

Project Cyclops: a Design Study of a System for Detecting Extraterrestrial Intelligent Life

The requirements in hardware, manpower, time and funding to conduct a realistic effort aimed at detecting the existence of extraterrestrial intelligent life are examined. The methods used are limited to present or near term future state-of-the-art techniques. Subjects discussed include: (1) possible methods of contact, (2) communication by electromagnetic waves, (3) antenna array and system facilities, (4) antenna elements, (5) signal processing, (6) search strategy, and (7) radio and radar astronomy.

Source record↗